The present invention concerns an arrangement: for detecting the type of occupancy of a seat in a motor vehicle.
It is known that airbags are provided in motor vehicles not only for the driver but also for the passenger. However, the passenger's airbag should be activated in an accident only when the passenger's seat is actually occupied by a passenger. If the passenger's seat is not occupied or is occupied only by baggage or a child's seat, activation of the airbag should be suppressed. Activation of an airbag in such cases would cause unnecessary repair costs and could actually be harmful for other occupants of the vehicle due to the additional increase in pressure generated in the vehicle interior. European Patent 0 458 102 A1 proposes deriving a force and/or pressure distribution pattern by means of force and/or pressure sensors to obtain detailed information regarding whether the passenger's seat is occupied by a person or baggage. An example of a force and/or pressure sensor is the pressure-dependent resistance mat (interlink mat) is described in German Patent DE 42 37 072 C1. In Patent Abstracts of Japan, vol. 018, no. 620 (M-1711), Nov. 25, 1994, JP 62 39 173, an arrangement for detecting seat occupancy is described. In this arrangement, several filters are provided to analyze by frequency selection the output signal of at least one sensor provided in the vehicle. A decision-making criterion for whether or not the vehicle seat is occupied by a passenger is obtained by comparing the frequency-selective components.